Effect of reverse manual wheelchair propulsion on shoulder kinematics,kinetics and muscular activity in persons with paraplegia

Objective: Shoulder pain after spinal cord injury (SCI) is attributed to increased mobility demands on the arms and negatively impacts independence and quality of life. Repetitive superior and posterior shoulder joint forces produced during traditional wheelchair (WC) locomotion can result in subacromial impingement if unopposed, as with muscular fatigue or weakness. ROWHEELS^® (RW), geared rear wheels that produce forward WC movement with backward rim pulling, could alter these forces.

Design: Cross sectional.

Setting: Research laboratory at a rehabilitation hospital.

Participants: Ten manual WC users with paraplegia.

Outcome measures: Propulsion characteristics and right upper extremity/trunk kinematics and shoulder muscle activity were collected during ergometer propulsion: (1) self-selected free speed reverse propulsion with RW, (2) matched-speed reverse (rSW), and (3) forward propulsion (fSW) with instrumented Smartwheels (SW). Inverse dynamics using right-side SW rim kinetics and kinematics compared shoulder kinetics during rSW and fSW.

Results: Free propulsion velocity, cycle distance and cadence were similar during RW, rSW and fSW. Overall shoulder motion was similar except that peak shoulder extension was significantly reduced in both RW and rSW versus fSW. Anteriorly and inferiorly directed SW rim forces were decreased during rSW versus fSW propulsion, but posteriorly and superiorly directed rim forces were significantly greater. Superior and posterior shoulder joint forces and flexor, adductor, and external rotation moments were significantly less during rSW, without a significant difference in net shoulder forces and moments. Traditional propulsive-phase muscle activity was significantly reduced and recovery-phase muscle activity was increased during reverse propulsion.

Conclusion: These results suggest that reverse propulsion may redirect shoulder demands and prevent subacromial impingement, thereby preventing injury and preserving independent mobility for individuals with paraplegia.     

Thematic analysis of qualitative data: AMEE Guide No. 131

Abstract

Thematic analysis is a widely used, yet often misunderstood, method of qualitative data analysis. It is a useful and accessible tool for qualitative researchers, but confusion regarding the method’s philosophical underpinnings and imprecision in how it has been described have complicated its use and acceptance among researchers. In this Guide, we outline what thematic analysis is, positioning it in relation to other methods of qualitative analysis, and describe when it is appropriate to use the method under a variety of epistemological frameworks. We also provide a detailed definition of a theme, as this term is often misapplied. Next, we describe the most commonly used six-step framework for conducting thematic analysis, illustrating each step using examples from our own research. Finally, we discuss advantages and disadvantages of this method and alert researchers to pitfalls to avoid when using thematic analysis. We aim to highlight thematic analysis as a powerful and flexible method of qualitative analysis and to empower researchers at all levels of experience to conduct thematic analysis in rigorous and thoughtful way.     

Does ablation of atrial fibrillation at the time of septal myectomy improve survival of patients with obstructive hypertrophic cardiomyopathy?

ObjectiveTo evaluate the outcomes after septal myectomy in patients with obstructive hypertrophic cardiomyopathy according to atrial fibrillation and surgical ablation of atrial fibrillation.MethodsWe reviewed patients with obstructive hypertrophic cardiomyopathy who underwent septal myectomy at the Mayo Clinic from 2001 to 2016. History of atrial fibrillation was obtained from patient histories and electrocardiograms. All-cause mortality was the primary end point.ResultsA total of 2023 patients underwent septal myectomy, of whom 394 (19.5%) had at least 1 episode of atrial fibrillation preoperatively. Among patients with atrial fibrillation, 76 (19.3%) had only 1 known episode, 278 (70.6%) had recurrent paroxysmal atrial fibrillation, and 40 (10.2%) had persistent atrial fibrillation. Surgical ablation was performed in 190 patients at the time of septal myectomy, including 148 with pulmonary vein isolation and 42 with the classic maze procedure. Among all patients, operative mortality was 0.4%, and there were no early deaths in patients undergoing surgical ablation. Over a median follow-up of 5.6 years, patients with preoperative atrial fibrillation had increased mortality (hazard ratio, 1.36; 95% confidence interval, 0.97-1.91; P = .070) after multivariable adjustment for comorbidities. When considering the impact of atrial fibrillation with or without surgical treatment, the adjusted hazard ratio for mortality in patients undergoing ablation compared with no ablation was 0.93 (95% confidence interval, 0.52-1.69; P = .824).ConclusionsAtrial fibrillation is present preoperatively in one-fifth of patients with obstructive hypertrophic cardiomyopathy undergoing myectomy and showed a trend toward higher all-cause mortality. Survival of patients undergoing septal myectomy with preoperative atrial fibrillation was similar between those who did and did not receive concomitant surgical ablation.     

Comparison of Patch Materials for Pulmonary Artery Reconstruction

Graphical abstract summarizing the overall results of our study comparing reintervention for a main or central branch pulmonary artery reconstruction site and various patch materials. Autologous pericardium was associate with the lowest reintervention and was free. Multivariable analysis demonstrated lack of superiority of homograft branch patch, which clearly has a much higher cost.

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Patterns of Use of Induction Therapy for T2N0 Esophageal Cancer

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Effects of Oxygen Supplementation on Injectable and Inhalant Anesthesia in C57BL/6 Mice

Oxygen supplementation is rarely considered when anesthetizing laboratory mice, despite reports that mice become profoundly hypoxic under anesthesia. Little is known about the effects of hypoxia on anesthetic performance. This article focuses on the effects of oxygen supplementation on physiologic parameters and depth of anesthesia in male and female C57BL/6 mice. Anesthesia was performed via common injectable anesthetic protocols and with isoflurane. Mice anesthetized with injectable anesthesia received one of 3 drug protocols. Low-dose ketamine/xylazine (100/8 mg/kg) was chosen to provide immobilization of mice, suitable for imaging procedures. Medium-dose ketamine/xylazine/acepromazine (100/10/1 mg/kg) was chosen as a dose that has been recommended for surgical procedures. High-dose ketamine/xylazine/acepromazine (150/12/3 mg/kg) was chosen after pilot studies to provide a long duration of a deep plane of anesthesia. We also tested the effects of oxygen supplementation on the minimum alveolar concentration (MAC) of isoflurane in mice. Mice breathed supplemental 100% oxygen, room air, or medical air with 21% oxygen. Anesthetized mice that did not receive supplemental oxygen all became hypoxic, while hypoxia was prevented in mice that received oxygen. Oxygen supplementation did not affect the MAC of isoflurane. At the high injectable dose, all mice not receiving oxygen supplementation died while all mice receiving oxygen supplementation survived. At low and medium doses, supplemental oxygen reduced the duration of the surgical plane of anesthesia (low dose with oxygen: 22 ± 14 min; low dose without supplementation: 29 ± 18 min; medium dose with oxygen: 43 ± 18 min; medium dose without supplementation: 61 ± 27 min). These results suggest that mice anesthetized with injectable and inhalant anesthesia without supplemental oxygen are routinely hypoxic. This hypoxia prolongs the duration of anesthesia with injectable drug protocols and affects survival at high doses of injectable anesthetics. Because of variable responses to injectable anesthetics in mice, oxygen supplementation is recommended for all anesthetized mice.

Anesthesia is frequently required for mice used in biomedical research, but anecdotal communications suggest that mice receive significantly less anesthetic monitoring and supportive care than do other research species. Monitoring of anesthetized mice is often minimal due to lack of specialized monitoring equipment, and the fact that many rodent surgeries are performed by a single person who acts as both surgeon and anesthetist. Supportive care during anesthesia is limited by a lack of supporting experimental evidence. The lack of monitoring and supportive care may increase the mortality rate in anesthetized mice.Previous studies have shown that mice anesthetized with both inhalant and injectable anesthetics without supplemental oxygen become profoundly hypoxic.^{1,6,8,9,19,26,39,41} While mice in these studies appear to recover normally from anesthesia, little is known about the effects of hypoxia on physiologic parameters, anesthetic depth, and perioperative mortality. Respiratory complications, including hypoxia and hypoventilation, are second only to cardiovascular complications as a cause of perioperative mortality in veterinary species, and in humans, hypoxemia accounts for over 50% of deaths under anesthesia.⁴ To mitigate the risk of hypoxia under anesthesia, oxygen supplementation is commonly provided to anesthetized humans and animals, but is rarely provided to mice in research settings.^6,19All anesthetics affect respiratory function; ketamine and isoflurane are particularly known to cause respiratory depression in mice and rats by impairing the normal physiologic responses to hypoxemia and hypercapnia.^{9,12,20,23,28} The peripheral chemoreceptors, primarily in the carotid body, normally sense dropping arterial partial pressure of oxygen (PaO₂) while central chemoreceptors located in the medulla sense changes in pH and rising partial pressure of carbon dioxide (PaCO₂).^22,23,29,40 Both sets of chemoreceptors compensate by initiating increases in respiratory rate and tidal volume.^{23,28,31,34,40} Injectable and inhalant anesthetic agents depress the function of these chemoreceptors, preventing the increases in respiration that compensate for hypoxia and hypoventilation.^22,29Pulse oximetry is commonly used to monitor peripheral oxygen saturation and detect the presence of hypoxia. Pulse oximeters use the difference in light absorption of oxygenated hemoglobin and deoxygenated hemoglobin in arterial blood to provide an estimate of arterial oxygen content, abbreviated as SpO₂.¹⁷ An SpO₂ of less than 90% to 95% generally corresponds to a PaO₂ of less than 60 to 80 mm Hg, which is considered hypoxic in most species of mammals.^7,17 Because of the small size of mice, species-specific pulse oximetry equipment is necessary to obtain this measurement. Therefore, measurement of SpO₂ in anesthetized mice is not routinely performed, meaning that hypoxia under anesthesia generally goes unrecognized, and is likely more common than is appreciated by our field.The purpose of this study was to confirm that mice become hypoxic after receiving a ketamine/xylazine based anesthetic admixture or isoflurane, which are commonly used anesthetics in mice and to investigate the effects of oxygen supplementation on anesthetic depth, physiologic values, and anesthetic requirements in these mice.^9,35 We hypothesized that mice not receiving supplemental oxygen would be hypoxic, as indicated by lower SpO₂ while anesthetized, and that supplemental oxygen would correct this hypoxia. We also hypothesized that oxygen supplementation would increase the doses of injectable and inhalant anesthesia necessary to maintain mice at a surgical plane of anesthesia.